Australia captain Michael Clarke completed a light training session today, but
will not make a call on his fitness until the morning of the Boxing Day Test
against Sri Lanka.

The 31 year-old injured his right hamstring in the first Test in Hobart last week and has been racing the clock to be fit to lead his side into a potential series-clinching victory.

He came through a variety of running drills under the watchful eye of physio Alex Kountouris in the team's final training session on Christmas Day, and remained optimistic of taking to the field in Melbourne tomorrow.

"It's going okay, thank you. It's improving every day," Clarke said of his hamstring. "I did a fair bit of running today in the indoor nets.

"I can't make a decision now. I need to wait and see how I pull up tomorrow morning, from the workload yesterday and then again at training today.

"Like I've said from day one, I'm still pretty positive that I'll be right for tomorrow."

Clarke will not have a last-minute fitness test before the game, with the decision to be made based on how he feels following today's training session.

"Tomorrow will be about how I pull up," he said. "My fitness test was today and now I need to see how I pull up from that to see whether I'm 100 per cent fit to play.

"There's every chance... it's natural for the injury to reoccur. So my decision has to be based on if I'm 100 per cent fit to perform at my best and whatever the consequences are after that... well, you deal with that every game you play so it's no different in this game."

Clarke also said he will only play if he is confident the injury will not affect his batting, and reiterated that whatever decision is made will be done for the benefit of the team.

"Having experts around me... Alex has been around international cricket for such a long time. He's seen me do my hamstrings on a few occasions - he's seen plenty of guys go through it," the skipper added.

"We'll try to make the best decision for the team - there's no doubt about that. I certainly won't go into the game tomorrow if I feel it's going to affect my batting.

"If I feel I can't perform at my best I certainly won't take any part, but if I can I'm really keen to get out there and be a part of it.

"If I cannot play my best in this Test I know I'm not doing the team justice by taking part."

Should Clarke fail to take his place in the side, Usman Khawaja will come in and Shane Watson will captain Australia.

"The team is in great hands. If I'm unavailable tomorrow, Watto will lead the team. I'm really confident in his captaincy ability on and off the field. He's a very good vice-captain and he's been around the group for a long time," Clarke said.

"If I don't play it'll make no difference in regards to captaincy. Watto will do a great job."